I ran into a webkit specific bug where my elements where added an extra display style (style="display:none;")
After some debugging I found what I think is a bug in the Ext.Element.getStyle method.
Here is the change to fix (always set back display from currentStyle)

Looks like 225/226 is when it was fixed in the 3.3.x branch in core. Not sure about your building problem, there may be an issue in the core jsb2 file we're not aware of as we haven't created a separate core build in a little while now.

I looked at the revision and it doesnt look like it would have fixed the bug to me.
Problem is that it use getComputedStyle to record previous state and el.style to reset it after.

This is an important to me as it makes my app unusable (makes node sticky display:none)
I'll try jsbuilder2 on another machine and stuff to try to build that;
but please let me know if theres anything else I could do to help test.